1. Field of the Invention
The present invention relates generally to orthodontic apparatus and, more particularly, to a tool for conveniently bending without damaging root canal files to selected curvatures of different radii within a predetermined range to allow the root canal files to precisely fit the curved portions of a root canal.
2. Description of the Prior Art
Root canal files or reamers are used in the cleaning of material present in the root canal of a human tooth and enlarging the root canal so that it may be filled. In the performance of a root canal procedure, a hole is first cut in the crown or exposed portion of the tooth, typically either in the biting surface of the tooth, for posterior teeth, or in the side of the tooth on the interior of the jaw for incisor teeth. Root canal files are then used to clean out the material present in the root canal, and to shape the root canal so that a tapered filling material may be inserted into the root canal to fill it.
When a root canal is being cleaned and shaped, a series of files increasing in size is used to gradually enlarge the root canal. A complete set will include a number of different sizes, with as many as eleven files in a set typically being used. The files are held between the thumb and forefinger of one hand by the dentist. Each file has one or more cutting surfaces thereon, with the cutting surfaces typically being in a spiral configuration. An examplary description of such a file may be found in U.S. Pat. No. 4,536,159 of Roane.
Unlike the files, root canals are seldom straight. If the files which are used deviate substantially from the original curvature of the root canal, the tooth may be irreversibly damaged. If the file is too straight and cuts through the side of the root in which the canal is located, which is referred to as a perforation of the root, the tooth must then be removed. If the tip of the file does not follow the curvature of the canal and bores a passage branching out from the root canal, which is referred to as ledging, surgical correction of the problem is necessitated. For a more detailed discussion of perforation and ledging, see my U.S. patent application Ser. No. 899,419, entitled Anti-Curvature Dental Root Canal Shaping File and filed concurrently with the present application. That application is hereby incorporated herein by reference.
It is therefore apparent that the files should be accurately bent prior to insertion into the root canal and use of the files to enlarge the root canal. Such bending of the files has typically been done crudely with hemostat pliers, tweezers or similar tool. Since the cutting edges of the files are very small and highly precise, great care must be taken to avoid damaging the file. It will be appreciated that it is relatively difficult to properly perform a very precise bend in a file with such inappropriate tools.
While the technology of bending metal includes a number of tools for bending leads of electrical components, such as U.S. Pat. No. 3,692,069, to Clendennen et al., and U.S. Pat. No. 4,399,844, to Kober et al., such tools are useless when it comes to making a precise yet delicate bend in a root canal file. The only art relating to dental bending tools is found in U.S. Pat. No. 1,108,493, to Federspiel, which discloses pliers for use in shaping loops of orthodontia wire. All dental pliers are relatively brute force instruments, for use in making curves in metal rather than for configuring root canal files to precisely fit the curvature of a root canal.
It is therefore apparent that there exists a substantial need for a tool which will be capable of imparting precise curves of various selected radii to any of a series of root canal files without damaging or distorting the cutting surfaces of the file. The solution to this need should also be relatively inexpensive, and capable of being used with all sizes of root canal files. Finally, a potential solution must also remedy the problems mentioned above without incurring relative disadvantage.